In the related art, as described in Japanese Unexamined Patent Application Publication No. 2003-63273, as a driving control device of a vehicle such as an automobile, a driving control device is known which performs driving control such that a host vehicle is driven at a certain setting vehicle speed set by a driver, in a case where a preceding vehicle does not exist in front of the host vehicle, and performs driving control such that the host vehicle is driven while maintaining an inter-vehicle distance between the preceding vehicle and the host vehicle, in a case where a preceding vehicle exists in front of the host vehicle.
In the device of Japanese Unexamined Patent Application Publication No. 2003-63273, in a case where the speed of the host vehicle becomes slower than the setting vehicle speed due to the speed of the preceding vehicle being slower than the setting vehicle speed and an overtaking lane exists, driving control is performed such that the host vehicle overtakes the preceding vehicle.